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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2020 Arm Limited
4 *
5 * Based on arch/arm64/kernel/machine_kexec_file.c:
6 * Copyright (C) 2018 Linaro Limited
7 *
8 * And arch/powerpc/kexec/file_load.c:
9 * Copyright (C) 2016 IBM Corporation
10 */
11
12#include <linux/ima.h>
13#include <linux/kernel.h>
14#include <linux/kexec.h>
15#include <linux/memblock.h>
16#include <linux/libfdt.h>
17#include <linux/of.h>
18#include <linux/of_fdt.h>
19#include <linux/random.h>
20#include <linux/slab.h>
21#include <linux/types.h>
22
23#define RNG_SEED_SIZE 128
24
25/*
26 * Additional space needed for the FDT buffer so that we can add initrd,
27 * bootargs, kaslr-seed, rng-seed, useable-memory-range and elfcorehdr.
28 */
29#define FDT_EXTRA_SPACE 0x1000
30
31/**
32 * fdt_find_and_del_mem_rsv - delete memory reservation with given address and size
33 *
34 * @fdt: Flattened device tree for the current kernel.
35 * @start: Starting address of the reserved memory.
36 * @size: Size of the reserved memory.
37 *
38 * Return: 0 on success, or negative errno on error.
39 */
40static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size)
41{
42 int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
43
44 for (i = 0; i < num_rsvs; i++) {
45 u64 rsv_start, rsv_size;
46
47 ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
48 if (ret) {
49 pr_err("Malformed device tree.\n");
50 return -EINVAL;
51 }
52
53 if (rsv_start == start && rsv_size == size) {
54 ret = fdt_del_mem_rsv(fdt, i);
55 if (ret) {
56 pr_err("Error deleting device tree reservation.\n");
57 return -EINVAL;
58 }
59
60 return 0;
61 }
62 }
63
64 return -ENOENT;
65}
66
67/**
68 * get_addr_size_cells - Get address and size of root node
69 *
70 * @addr_cells: Return address of the root node
71 * @size_cells: Return size of the root node
72 *
73 * Return: 0 on success, or negative errno on error.
74 */
75static int get_addr_size_cells(int *addr_cells, int *size_cells)
76{
77 struct device_node *root;
78
79 root = of_find_node_by_path("/");
80 if (!root)
81 return -EINVAL;
82
83 *addr_cells = of_n_addr_cells(root);
84 *size_cells = of_n_size_cells(root);
85
86 of_node_put(root);
87
88 return 0;
89}
90
91/**
92 * do_get_kexec_buffer - Get address and size of device tree property
93 *
94 * @prop: Device tree property
95 * @len: Size of @prop
96 * @addr: Return address of the node
97 * @size: Return size of the node
98 *
99 * Return: 0 on success, or negative errno on error.
100 */
101static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
102 size_t *size)
103{
104 int ret, addr_cells, size_cells;
105
106 ret = get_addr_size_cells(&addr_cells, &size_cells);
107 if (ret)
108 return ret;
109
110 if (len < 4 * (addr_cells + size_cells))
111 return -ENOENT;
112
113 *addr = of_read_number(prop, addr_cells);
114 *size = of_read_number(prop + 4 * addr_cells, size_cells);
115
116 return 0;
117}
118
119#ifdef CONFIG_HAVE_IMA_KEXEC
120/**
121 * ima_get_kexec_buffer - get IMA buffer from the previous kernel
122 * @addr: On successful return, set to point to the buffer contents.
123 * @size: On successful return, set to the buffer size.
124 *
125 * Return: 0 on success, negative errno on error.
126 */
127int __init ima_get_kexec_buffer(void **addr, size_t *size)
128{
129 int ret, len;
130 unsigned long tmp_addr;
131 unsigned long start_pfn, end_pfn;
132 size_t tmp_size;
133 const void *prop;
134
135 prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
136 if (!prop)
137 return -ENOENT;
138
139 ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
140 if (ret)
141 return ret;
142
143 /* Do some sanity on the returned size for the ima-kexec buffer */
144 if (!tmp_size)
145 return -ENOENT;
146
147 /*
148 * Calculate the PFNs for the buffer and ensure
149 * they are with in addressable memory.
150 */
151 start_pfn = PHYS_PFN(tmp_addr);
152 end_pfn = PHYS_PFN(tmp_addr + tmp_size - 1);
153 if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn)) {
154 pr_warn("IMA buffer at 0x%lx, size = 0x%zx beyond memory\n",
155 tmp_addr, tmp_size);
156 return -EINVAL;
157 }
158
159 *addr = __va(tmp_addr);
160 *size = tmp_size;
161
162 return 0;
163}
164
165/**
166 * ima_free_kexec_buffer - free memory used by the IMA buffer
167 */
168int __init ima_free_kexec_buffer(void)
169{
170 int ret;
171 unsigned long addr;
172 size_t size;
173 struct property *prop;
174
175 prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
176 if (!prop)
177 return -ENOENT;
178
179 ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
180 if (ret)
181 return ret;
182
183 ret = of_remove_property(of_chosen, prop);
184 if (ret)
185 return ret;
186
187 return memblock_phys_free(addr, size);
188}
189#endif
190
191/**
192 * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
193 *
194 * @fdt: Flattened Device Tree to update
195 * @chosen_node: Offset to the chosen node in the device tree
196 *
197 * The IMA measurement buffer is of no use to a subsequent kernel, so we always
198 * remove it from the device tree.
199 */
200static void remove_ima_buffer(void *fdt, int chosen_node)
201{
202 int ret, len;
203 unsigned long addr;
204 size_t size;
205 const void *prop;
206
207 if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
208 return;
209
210 prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
211 if (!prop)
212 return;
213
214 ret = do_get_kexec_buffer(prop, len, &addr, &size);
215 fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
216 if (ret)
217 return;
218
219 ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
220 if (!ret)
221 pr_debug("Removed old IMA buffer reservation.\n");
222}
223
224#ifdef CONFIG_IMA_KEXEC
225/**
226 * setup_ima_buffer - add IMA buffer information to the fdt
227 * @image: kexec image being loaded.
228 * @fdt: Flattened device tree for the next kernel.
229 * @chosen_node: Offset to the chosen node.
230 *
231 * Return: 0 on success, or negative errno on error.
232 */
233static int setup_ima_buffer(const struct kimage *image, void *fdt,
234 int chosen_node)
235{
236 int ret;
237
238 if (!image->ima_buffer_size)
239 return 0;
240
241 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
242 "linux,ima-kexec-buffer",
243 image->ima_buffer_addr,
244 image->ima_buffer_size);
245 if (ret < 0)
246 return -EINVAL;
247
248 ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
249 image->ima_buffer_size);
250 if (ret)
251 return -EINVAL;
252
253 pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
254 image->ima_buffer_addr, image->ima_buffer_size);
255
256 return 0;
257}
258#else /* CONFIG_IMA_KEXEC */
259static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
260 int chosen_node)
261{
262 return 0;
263}
264#endif /* CONFIG_IMA_KEXEC */
265
266/*
267 * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
268 *
269 * @image: kexec image being loaded.
270 * @initrd_load_addr: Address where the next initrd will be loaded.
271 * @initrd_len: Size of the next initrd, or 0 if there will be none.
272 * @cmdline: Command line for the next kernel, or NULL if there will
273 * be none.
274 * @extra_fdt_size: Additional size for the new FDT buffer.
275 *
276 * Return: fdt on success, or NULL errno on error.
277 */
278void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
279 unsigned long initrd_load_addr,
280 unsigned long initrd_len,
281 const char *cmdline, size_t extra_fdt_size)
282{
283 void *fdt;
284 int ret, chosen_node, len;
285 const void *prop;
286 size_t fdt_size;
287
288 fdt_size = fdt_totalsize(initial_boot_params) +
289 (cmdline ? strlen(cmdline) : 0) +
290 FDT_EXTRA_SPACE +
291 extra_fdt_size;
292 fdt = kvmalloc(fdt_size, GFP_KERNEL);
293 if (!fdt)
294 return NULL;
295
296 ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
297 if (ret < 0) {
298 pr_err("Error %d setting up the new device tree.\n", ret);
299 goto out;
300 }
301
302 /* Remove memory reservation for the current device tree. */
303 ret = fdt_find_and_del_mem_rsv(fdt, __pa(initial_boot_params),
304 fdt_totalsize(initial_boot_params));
305 if (ret == -EINVAL) {
306 pr_err("Error removing memory reservation.\n");
307 goto out;
308 }
309
310 chosen_node = fdt_path_offset(fdt, "/chosen");
311 if (chosen_node == -FDT_ERR_NOTFOUND)
312 chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
313 "chosen");
314 if (chosen_node < 0) {
315 ret = chosen_node;
316 goto out;
317 }
318
319 ret = fdt_delprop(fdt, chosen_node, "linux,elfcorehdr");
320 if (ret && ret != -FDT_ERR_NOTFOUND)
321 goto out;
322 ret = fdt_delprop(fdt, chosen_node, "linux,usable-memory-range");
323 if (ret && ret != -FDT_ERR_NOTFOUND)
324 goto out;
325
326 /* Did we boot using an initrd? */
327 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", &len);
328 if (prop) {
329 u64 tmp_start, tmp_end, tmp_size;
330
331 tmp_start = of_read_number(prop, len / 4);
332
333 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", &len);
334 if (!prop) {
335 ret = -EINVAL;
336 goto out;
337 }
338
339 tmp_end = of_read_number(prop, len / 4);
340
341 /*
342 * kexec reserves exact initrd size, while firmware may
343 * reserve a multiple of PAGE_SIZE, so check for both.
344 */
345 tmp_size = tmp_end - tmp_start;
346 ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size);
347 if (ret == -ENOENT)
348 ret = fdt_find_and_del_mem_rsv(fdt, tmp_start,
349 round_up(tmp_size, PAGE_SIZE));
350 if (ret == -EINVAL)
351 goto out;
352 }
353
354 /* add initrd-* */
355 if (initrd_load_addr) {
356 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-start",
357 initrd_load_addr);
358 if (ret)
359 goto out;
360
361 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-end",
362 initrd_load_addr + initrd_len);
363 if (ret)
364 goto out;
365
366 ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
367 if (ret)
368 goto out;
369
370 } else {
371 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-start");
372 if (ret && (ret != -FDT_ERR_NOTFOUND))
373 goto out;
374
375 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-end");
376 if (ret && (ret != -FDT_ERR_NOTFOUND))
377 goto out;
378 }
379
380 if (image->type == KEXEC_TYPE_CRASH) {
381 /* add linux,elfcorehdr */
382 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
383 "linux,elfcorehdr", image->elf_load_addr,
384 image->elf_headers_sz);
385 if (ret)
386 goto out;
387
388 /*
389 * Avoid elfcorehdr from being stomped on in kdump kernel by
390 * setting up memory reserve map.
391 */
392 ret = fdt_add_mem_rsv(fdt, image->elf_load_addr,
393 image->elf_headers_sz);
394 if (ret)
395 goto out;
396
397 /* add linux,usable-memory-range */
398 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
399 "linux,usable-memory-range", crashk_res.start,
400 crashk_res.end - crashk_res.start + 1);
401 if (ret)
402 goto out;
403
404 if (crashk_low_res.end) {
405 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
406 "linux,usable-memory-range",
407 crashk_low_res.start,
408 crashk_low_res.end - crashk_low_res.start + 1);
409 if (ret)
410 goto out;
411 }
412 }
413
414 /* add bootargs */
415 if (cmdline) {
416 ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
417 if (ret)
418 goto out;
419 } else {
420 ret = fdt_delprop(fdt, chosen_node, "bootargs");
421 if (ret && (ret != -FDT_ERR_NOTFOUND))
422 goto out;
423 }
424
425 /* add kaslr-seed */
426 ret = fdt_delprop(fdt, chosen_node, "kaslr-seed");
427 if (ret == -FDT_ERR_NOTFOUND)
428 ret = 0;
429 else if (ret)
430 goto out;
431
432 if (rng_is_initialized()) {
433 u64 seed = get_random_u64();
434
435 ret = fdt_setprop_u64(fdt, chosen_node, "kaslr-seed", seed);
436 if (ret)
437 goto out;
438 } else {
439 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
440 "kaslr-seed");
441 }
442
443 /* add rng-seed */
444 if (rng_is_initialized()) {
445 void *rng_seed;
446
447 ret = fdt_setprop_placeholder(fdt, chosen_node, "rng-seed",
448 RNG_SEED_SIZE, &rng_seed);
449 if (ret)
450 goto out;
451 get_random_bytes(rng_seed, RNG_SEED_SIZE);
452 } else {
453 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
454 "rng-seed");
455 }
456
457 ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
458 if (ret)
459 goto out;
460
461 remove_ima_buffer(fdt, chosen_node);
462 ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen"));
463
464out:
465 if (ret) {
466 kvfree(fdt);
467 fdt = NULL;
468 }
469
470 return fdt;
471}